<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        for (let i = 0; i < 5; i++) {
            for (let j = 0; j < i+1; j++) {
                document.write("*");               
            }
            document.write("<br />");
        }

        for (let i = 0; i < 5; i++) {
            for (let j = 0; j < 5; j++) {
                document.write("*");               
            }
            document.write("<br />");
        }

        for (let i = 0; i < 5; i++) {
            for (let j = 0; j < 5-i; j++) {
                document.write("*");               
            }
            document.write("<br />");
        }
    </script>
</head>
<body>
    
</body>
</html>